Thermoelectric material having a rhombohedral crystal structure

Abstract

Thermoelectric materials with a high Seebeck coefficient and a large power factor are provided. The materials are impact resistant and resistant to heat-distortion. Such materials include a rare earth element, Bi, and Te and have a rhombohedral crystal structure. In some examples, the rare earth element is selected from the group consisting of Ce, Sm and Yb. Such materials can be formed as films with a thickness of from 0.01 to 500 μm on a resin substrate. Production methods may include laminating different types of layers of thickness of 20 nm or less and heat-treating the resultant composition-modulated composite. The material may be separated from a substrate for sintering.

1. A thermoelectric material according to the formula R x Bi y(1-b) Te (100-x-y)(1-a) Se a(100-x-y) Sb yb , wherein R includes at least one element selected from a group consisting of Ce, Sm, and Yb, x, y, a, and b satisfy the expressions 0.05≦x<20, 20≦y≦75, 0≦a≦0.5, 0≦b≦0.8, and further wherein a main phase of the thermoelectric material has a rhombohedral crystal structure. 
     
     
       2. The thermoelectric material of  claim 1 , wherein a=0. 
     
     
       3. The thermoelectric material of  claim 2 , wherein an average crystal grain size is greater than about 1 μm. 
     
     
       4. The thermoelectric material of  claim 1 , wherein b=0. 
     
     
       5. The thermoelectric material of  claim 4 , wherein an average crystal grain size is greater than about 1 μm. 
     
     
       6. The thermoelectric material of  claim 1 , according to the formula R x Bi y(1-b) Te (100-x-y)(1-a) Se a(100-x-y) Sb yb , wherein a=0 and b=0. 
     
     
       7. The thermoelectric material of  claim 6 , wherein an average crystal grain size is greater than about 1 μm. 
     
     
       8. The thermoelectric material of  claim 1 , wherein an average crystal grain size is greater than about 1 μm. 
     
     
       9. The thermoelectric material of  claim 1 , wherein at least one crystal phase has a strongest X-ray diffraction line having a width at half maximum of less than about 0.5°. 
     
     
       10. The thermoelectric material of  claim 1 , wherein an index of alignment A=I(222)/I(−110) is at least about 10, wherein I(222) and I(−110) are relative diffraction intensities with respect to associated baseline intensities for X-ray diffraction associated with indices (222) and (−110), respectively. 
     
     
       11. A thermoelectric film comprising the thermoelectric material of  claim 1 , where the film has a thickness between about 0.01 μm and 500 μm. 
     
     
       12. The thermoelectric film of  claim 11 , further comprising a resin substrate, and the thermoelectric film is situated on the resin substrate.